According to the Round-Up label, it is safe to plant 3 days after application. The main ingredient is glyphosate which does not travel in the soil but is held there until it degrades. Many gardeners use Round-Up to clear an area of weeds and then plant. Either do it now to remove weeds or wait until a week or so before you're ready to plant next spring. If you use the herbicide now to kill weeds, you'll want to wait several days for the weeds to die completely, then rake them out and cover the soil with mulch to prevent additional weeds from sprouting this winter.

To remove any doubt at all about the safety of using herbicides in the vegetable garden, you might want to remove the weeds by pulling them up, roots and all, then raking the debris from the garden area and covering it with 3-4 inches of organic material (aged compost or aged manure) to prevent weeds from growing in the area over the winter months. In the spring you can work the organic matter into the soil to help loosen and enrich it, then plant your veggies.